Reloading - How to get the best case length for a given gun

[Fredo]

Hi reloaders,

I was wondering if there is a way to assess the best case length for a lever action rifle.

Some people seems to believe that the case trim length is the gold standard, but there are variations between this and the maximum case length. How can I get the best value for a given rifle?

Anybody got any idea on this?

Thanks for your answers.

[elkhunter11]

The maximum case length, is based on the chamber dimensions. If the case is much too long, it simply won't chamber. If it is slightly too long, it may chamber with some difficulty, and cause a serious increase in chamber pressure, as it clamps down on the bullet, as it hits the end of the chamber. The safest bet, is to trim to the the suggested trim length, as soon as the case exceeds the standard case length for the cartridge.

Hornady has been trimming some cases shorter than standard, so that they can crimp the case properly with some of their bullets, and if you intend to use those particular bullets, you may have to trim your cases to the same length, in order to crimp the cases in the cannelure of those bullets, and still have an overall cartridge length, that still feeds properly in your rifle.

The bottom line, is to use the standard trim length, unless you are loading some of the Hornady specialty bullets, like the FTX. If you are using those bullets, then you may have to trim the cases shorter, to allow them to cycle properly, if you crimp in the cannelure.

[qwert]

You can make a chamber cast and measure the actual chamber neck length and a fire-formed case to calculate the maximum case length.
Google "cerrosafe"

Or you can use a variation on the sliding bullet in a semi loose case neck technique many use to determine distance to the lands but using a Sinclair or shop-built neck gauge.

http://www.sinclairintl.com/reloadin...prod32925.aspx

http://forum.snipershide.com/snipers...se-prep-4.html

http://www.longrangehunting.com/foru...r-rifle-51713/

http://varmintal.com/arelo.htm

Google "sinclair chamber neck length gauge"
also
Google "measure chamber neck length"

CAUTION - This is a critical dimension and an over-length neck can cause serious over-pressure.

Good Luck, YMMV

[CNP]

It seems you are implying that there is an optimum case length for your rifle. All cases being the same length and having the same bullet seating tension, would be the optimum. Let your reloading components decide the best cartridge you can load. The only length adjustment you could dicker with is the cartridge overall length (not to be confused with the maximum case length). I do not crimp any of the bullets I am using.

[Fredo]

Thanks for your answers.

I'm gonna give a try to those chamber length gage.

[qwert]

Further to my post # 3,

You could also use a fired neck OD sized plug and the cleaning rod with 2 stops method many use to measure COAL.

Good Luck, YMMV

[Fredo]

I don't know this method, I use a caliper for COAL.

[6.5 shooter]

Originally Posted by ehntr

It seems you are implying that there is an optimum case length for your rifle. All cases being the same length and having the same bullet seating tension, would be the optimum. Let your reloading components decide the best cartridge you can load. The only length adjustment you could dicker with is the cartridge overall length (not to be confused with the maximum case length). I do not crimp any of the bullets I am using.

x2

Case length if it grows excessively 1-2 firings may indicate a head space problem. I trim my cases to whatever the manuals suggest then keep an eye on them. Most times the case will grow a bit then "settle" at that length and stay there for several reloads before needing to be trimmed again but by then the brass is usually worn out in some other area eg: primer pockets etc.

[qwert]

Originally Posted by Fredo

I don't know this method, I use a caliper for COAL.

From my post # 3,
You could also use a fired neck OD sized plug and the cleaning rod with 2 stops method many use

to measure COAL.

I should have more correctly said,
to determine OAL to lands, and calculate desired COAL.

I am not a big fan of seating by measuring COAL and much prefer to measure to ogive, but the cleaning rod with stops method does work well to obtain the initial COAL on the lands measurement as described in this link.

http://forum.snipershide.com/snipers...start-oal.html

Good Luck, YMMV

[elkhunter11]

Originally Posted by qwert

From my post # 3,
You could also use a fired neck OD sized plug and the cleaning rod with 2 stops method many use

to measure COAL.

I should have more correctly said,
to determine OAL to lands, and calculate desired COAL.

I am not a big fan of seating by measuring COAL and much prefer to measure to ogive, but the cleaning rod with stops method does work well to obtain the initial COAL on the lands measurement as described in this link.

http://forum.snipershide.com/snipers...start-oal.html

Good Luck, YMMV

The OP was asking about case length, and you seem to be talking about the cartridge overall length. The two are entirely different things.

[Fredo]

Actually, I'm gonna just trim a batch down to case trim length, and see what happens after they expand, I will raise the case length by 0.001 implements up to the maximum case length minus 0.002.

[elkhunter11]

I will raise the case length by 0.001 implements up to the maximum case length minus 0.002.

Which will in effect, accomplish absolutely nothing, except waste your time.

[Fredo]

Interesting. No influence at all in pressure or seating? I assume it may lower the COAL.

[qwert]

Originally Posted by elkhunter11

The OP was asking about case length, and you seem to be talking about the cartridge overall length. The two are entirely different things.

The OP was asking how to determine the best case length for an individual rifle. This requires measuring the actual chamber length as a way to determine the proper case trim length. Many sources report that most production chambers are cut with significant excess length. Many case trimmers actually cut the case shorter than SAMMI standard which compounds the problem. Some people prefer to run longer than SAAMI standard case neck length for a variety of reasons.

You correctly described the result of a case that is too long for an individual chamber and the best way to avoid this problem, but you also failed to answer the OP's question.

I suggested there were several ways to measure the chamber length and provided links to further information and discussion.

The Sinclair Chamber Length Gauge
http://www.sinclairintl.com/reloadin...prod32925.aspx

here shown installed in shortened case
http://i664.photobucket.com/albums/v...hidech1014.jpg

then this shortened case & gauge assembly can be used to measure the chamber length using either the neck friction or the cleaning rod with 2 rod stops method which is more often used to measure COAL with bullet on lands as described here
http://forum.snipershide.com/snipers...start-oal.html

I also posted links to descriptions of the poor mans procedure using a shortened case with seated bullet and movable neck ring which can be used with the common neck friction method.

The OP did not ask if this work was worth the time and effort and I did not offer an opinion.

YMMV

[elkhunter11]

Originally Posted by Fredo

Interesting. No influence at all in pressure or seating? I assume it may lower the COAL.

Just how would shortening or lengthening the case by a few thousandths of an inch, effect the COAL? If you want to change the COAL, then simply adjust your seating die.

[dgitz]

If you have a set COAL you want to stick to then increasing your case length would require you to seat your bullet deeper to maintain the same COAL.

[elkhunter11]

Originally Posted by dgitz

If you have a set COAL you want to stick to then increasing your case length would require you to seat your bullet deeper to maintain the same COAL.

Unless you readjust your seating die, your COAL won't change, just because the case length varies by a few thousandth of an inch.

[tchardy1972]

Originally Posted by dgitz

If you have a set COAL you want to stick to then increasing your case length would require you to seat your bullet deeper to maintain the same COAL.

How do you figure that? Your trimmer will leave a difference of .001-.002 on just about every case you trim. Are you saying that you adjust your seating die separately for each case to make up for this difference in case length.

[Lefty-Canuck]

Originally Posted by elkhunter11

Unless you readjust your seating die, your COAL won't change, just because the case length varies by a few thousandth of an inch.

Exactly....COAL is not the same thing as trim to length.

LC

[dgitz]

No your seating die is set to give you your desired COAL. If the case length is noticeably too long then the bullet would appear to be seated deeper.

I worded it wrong in my first post.

[Full Curl Earl]

Also of note, this is a lever gun and I can almost guarantee that the OaL will change in the tube by a thou or two.

[260 Rem]

Regarding the question of optimum case/trim length for a lever gun --- I would personally go with the recommended trim length given in a load manual... I sincerely doubt anybody has a story suggesting that optimizing trim length improved the performance in a lever gun? If you really need to know, the Sinclair tool looks like a decent option, or you could just use a FB bullet, reversed in a split neck. Just be aware the latter "measurement" could vary somewhat depending on throat erosion or by the soft copper slightly entering the throat of the bore.

[qwert]

Originally Posted by 260 Rem

If you really need to know, the Sinclair tool looks like a decent option, or you could just use a FB bullet, reversed in a split neck. Just be aware the latter "measurement" could vary somewhat depending on throat erosion or by the soft copper slightly entering the throat of the bore.

We are not trying to measure the throat, we are looking for the end of the chamber which will be the same diameter as the OD of a fire-formed case neck. An inverted bullet will be throat bore diameter or slightly smaller, and will require a ring of case neck to be applied flush with the flat base of the bullet. We need a gauge that will be larger than the throat bore diameter and ideally just a little smaller than the neck portion of the chamber, a thick case wall would be desirable for max OD while still gripping the bullet.

Some will suggest that the end of the chamber may be eroded into the throat as a result of many firings of cases that were trimmed too short.

[Fredo]

Mmm as often with reloading, a simple question rises complex solutions!
I'll manage with the case trim length and seating die.

[6.5 shooter]

Trim the case to manual specs. Period

If you want to fool around with OACL (overall cartridge length) fill your boots.

I have found that seating the bullet a few thousands off the lands works 99.9% of the time. Powder choice and volume, as well as primers and bullet choice, make much larger changes to ones overall results, then having brass that is XXX shorter or XXX times longer.

Besides eroding lands will do more to affect accuracy then the chamber flowing into the the throat of the rifle.

Now if your brass is too long then you have a totally different and dangerous problem on your hands.

[SirQuincyM]

I've just read all the replies and it appears the that you are still a little confused on the posted answers... First; in all my years of reloading
COAL has meant "Cartridge over all length" .... that means the length of
the loaded round from Case head to bullet tip. Seeing that the original question was regarding the trimming of the "case" to the proper length; and
that may still be your question?? If your interpretation of COAL is "Case over all Length" .... then that is incorrect. If you're looking for the case length for and individual rifle; then just trim it to the spec length.... case length is the least of the variables that will affect your accuracy.

[Fredo]

I wanted to know if variable values in case length somewhat affected accuracy, and if there was a way to read the most suitable case length for a given rifle chamber.
Seems it does not affect accuracy, so I'm gonna stick to the book.

Thanks everyone for your contribution, greatly appreciated.